Yes I get that. But are you aware of the chemical breakdown of distilled water? I don't use it so I don't have any idea. Perhaps next to nothing. I have no idea.

But I can tell you that most orchids need a little nutritional boost from time to time. I use 20-20-20 Jacks all purpose. If you are using nothing but distilled water, that could be why you are seeing bulbs go orange.
Nitrogen, Phosphorous, Potassium, Calcium, Magnesium, and then with trace elements, your plants might be happier.
When your Miltoniopsis bloom, how big are the flowers and how many are there on each spike? This would be useful to know.

Distilled water should be as close to pure H20 as you can get. It won't contain minerals or other nutrients.

Australis said: Distilled water should be as close to pure H20 as you can get. It won't contain minerals or other nutrients.

And, my early Orchid training ground was this tall window wall, all along our research labs. I spent years watering at lunch time. All labs had one faucet dedicated to distilled water and I never used it to water the Orchids. I got my training from my Chemist boss!! Better use rain water if your city water is too hard, and do fertilize your plants.

OK all you scientists out there. The water in FL is hard and we have a water softener to bring the pH to neutral but, of course, it uses salts to do that. We drink RO water and take suppliments to make up for the natural minerals it lacks. I don't really have any good options for collecting rainwater.
So, I know the softened water is not good but what about the RO? Should I be adding specific fertilizers to make up for the minerals it is missing?

They do make a special fertilizer just for Florida's situation. I just do not remember what it was off hand.

Yes, I would think the RO is too pure for plants and I would add some specific minerals back in.

Btw I seem to remember that Kathy Puckett/Boojum had an RO system installed at her previous place. She might be able to tell you exactly what she added in.